Various systems have heretofore been proposed for admixture of water vapor into the fuel-air mixture of an internal combustion engine. The general approach has been to inject water into either the carburetor or intake manifold of the engine. One problem in the prior art is due to the fact that the beneficial combustion influencing effects of the water vapor primarily occur at high engine R.P.M. Accordingly, the prior art has sought to influence the rate of supply of water to the engine as a function of engine R.P.M. by using various indicia of R.P.M. such as intake manifold pressure. Consequently, the prior art systems have been quite complicated.
If a technique could be devised for injecting water directly into each cylinder at an appropriate time during each combustion cycle, the rate of water supply to the engine may automatically be made a function of engine R.P.M. Further, water may be injected at a time not necessarily co-extensive with the opening of the fuel intake valve, providing additional freedom for optimization of the combustion.